A zooming user interface (ZUI) is a type of graphical user interface (GUI) in which the scale of a viewed area is changed in order to view more detail or less, and to browse through and among different visual display elements such as images, shapes, documents, or videos. Display elements may be added to a workspace referred to as a ‘canvas’ to create a zoomable presentation in which details and subtopics can be presented through zooming in and out to reveal more or less detail. The canvas is larger than a viewing window generated on a device display screen, and a user can scroll a viewing window to view different display elements disposed on different regions of the canvas. The ZUI differs from a normal canvas in that the user may zoom in or out onto a particular display element. Display elements can be inserted anywhere among the presentation content, in addition to grouping display elements within frames. Users can pan across the canvas in two dimensions (in 2D) and zoom into objects of interest. Display elements present inside a zoomed region can in turn be zoomed themselves to reveal additional detail, allowing for recursive nesting and an arbitrary level of zoom. For example, as a user zooms into a text object, the text may be represented initially as a small dot, then as a thumbnail image, next as a complete page and finally as a magnified view of a portion of the page focused on a key passage from the text. Thus, ZUIs use zooming as the primary metaphor for browsing through multivariate or hyperlinked information.
FIG. 1A-1C are an illustrative drawings showing three different portions of a canvas at three different zoom levels viewed through a viewing window. FIG. 1A shows a viewing window 3 through which portions of display elements 4 and 6 disposed on a canvas 2 are visible but in which display elements 8-14 on the canvas 2 are not visible. The four arrows in FIG. 1A indicate the ability to move the viewing window so as to pan across the canvas 2. FIG. 1B shows a zoomed out view of the same canvas 2 in which display elements 4-14 are visible through the viewing window 3. FIG. 1C shows a zoomed in view of display element 6 on the same canvas 2 through the viewing window 3.